Search

BACKGROUND: We conducted the first national TB prevalence survey to provide accurate estimates of bacteriologically confirmed pulmonary TB disease among adults aged ≥15 years in 2014. METHODS: A TB symptoms screen and chest X-ray (CXR) were used to identify presumptive TB cases who submitted two sputum samples for smear microscopy, liquid and solid culture. Bacteriological confirmation included acid-fast bacilli smear positivity confirmed using Xpert ® MTB/RIF and/or culture. Prevalence estimates were calculated using random effects logistic regression with multiple imputations and inverse probability weighting. RESULTS: Of 43,478 eligible participants, 33,736 (78%) were screened; of these 5,820 (17%) presumptive cases were identified. There were 107 (1.9%) bacteriologically confirmed TB cases, of which 23 (21%) were smear-positive. The adjusted prevalences of smear-positive and bacteriologically confirmed TB disease were respectively 82/100,000 population (95% CI 47-118/100,000) and 344/100,000 (95% CI 268-420/100,000), with an overall all-ages, all-forms TB prevalence of 275/100,000 population (95% CI 217-334/100,000). TB prevalence was higher in males, and age groups 35-44 and ≥65 years. CXR identified 93/107 (87%) cases vs. 39/107 (36%) using the symptom screen. CONCLUSION: Zimbabwe TB disease prevalence has decreased relative to prior estimates, possibly due to increased antiretroviral therapy coverage and successful national TB control strategies. Continued investments in TB diagnostics for improved case detection are required.

Setting: In countries with high human immunodeficiency virus prevalence, laboratory diagnosis of pulmonary tuberculosis with the standard Ziehl-Neelsen (ZN) technique is characterised by low sensitivity., Objective: To compare test characteristics of direct microscopy, the concentration method and the Mycobacteria Growth Indicator Tube (MGIT)., Design: Three hundred specimens from patients diagnosed with pulmonary tuberculosis were tested for the presence of mycobacteria. Specimens were stained with ZN, decontaminated by adding 4% NaOH, concentrated by centrifuging and processed in MGIT broth. The gold standard was defined as a positive MGIT culture or a positive acid-fast bacilli smear of material obtained from a negative culture after 42 days., Results: A total of 44 (14.7%) specimens were contaminated. Of 256 valid specimens, 234 (91.4%) were positive according to the gold standard definition. Decontamination and concentration of the sample increased the sensitivity of direct microscopy from 67.5% to 87.1%. Specificity remained unchanged (95.5%). The overall median time to detection of MGIT culture-positive specimens was 5 days, ranging from 4 (direct smear-positive specimens) to 12 days (concentration smear-negative specimens)., Conclusion: The concentration method substantially increases the sensitivity of direct microscopy without much extra input. The MGIT culture technique has considerable advantages, but its relatively high contamination rate and its high cost make it a less recommendable option for widespread use in routine district laboratories.